Water of various types requires treatment for removal of impurities from the water. Such treatments often involve filtration, sometimes via a sand filtration system.
The water that requires treatment can be water from a stream, from an underground aquifer, from a mining operation, from a flue gas scrubbing operation or the like. The water could alternatively be brackish or salty water from ocean incursion into rivers and streams; the water can be muddy river water or waste water from residential or industrial use.
Sometimes the water has chemicals, including organic and/or inorganic compounds and pathogens in it.
In many instances, the water is treated with lime to raise its pH to a sufficiently high level to neutralize pathogens by lime stabilization. The lime stabilization can occur by the use of calcium oxide or calcium carbonate, such as lime, quick lime, lime kiln dust, cement kiln dust, dolomite lime, or various other forms of lime suited to raise the pH of the water that is being treated, generally because of the relatively high alkalinity of lime.
Following the treatment of water with lime in some form, the thus treated liquid is generally referred to as “milk of lime”. The milk of lime is generally largely in the form of a solution, but frequently has substantial undissolved particles of lime, called “grit”, as well as other impurities, which can include dirt, salt, unreacted lime particles, charred or hard-burnt lime, among some of the impurities that can exist within lime-treated water.